During the past ten years oral contraceptive agents have become increasingly popular and it is estimated that approximately 20 million women are now using them. It is also becoming increasingly apparent that in many women these agents are associated with a variety of adverse side effects. Prominent among these are changes in liver function which result in alterations in the metabolism of fats, proteins and carbohydrates and in some instances hepatic tumors have also been reported. In addition it is now fairly well established that "the pill" changes the requirements for a number of essential nutrients. Aflatoxin has been characterized as one of the most potent hepatocarcinogens known and has been isolated from human food supplies in all parts of the world. Since in certain areas avoidance of this toxin is difficult it seems likely that some oral contraceptive users might also be exposed to aflatoxin. In order to study the possibility that oral contraceptive use may alter resistance to aflatoxin toxicity we intend to utilize the animal model developed in our laboratory to test the effect of Enovid E, administered either during aflatoxin-induced tumor formation or else during aflatoxin-induced tumor growth, on indices which are characteristic of aflatoxicosis in rats. These include: growth, morbidity, mortality, tumor incidence and severity, histopathology and lipid biochemistry.